Automatic apparatus for producing members from powders



Nov. 24, 1964 c. DE IBEL ETAL 3,157,914

AUTOMATIC APPARATUS FOR PRODUCING MEMBERS FROM POWDERS Filed'April 10, 1962 4 Sheets-Sheet l WITNESSES- 1 INVENTORS Charles Deibel ,Fronk Emley ond Olof A. Olousen.

ATTO NEY Fig. I

Nov. 24, 1964 DEIBEL ETAL 3,157,914

AUTOMATIC APPARATUS FOR PRODUCING MEMBERS FROM POWDERS Filed April 10, 1962 4 Sheets-Sheet 2 PUMP POWER SUPPLY Nov. 24, 1964 c. DElBEL ETAL AUTOMATIC APPARATUS FOR PRODUCING MEMBERS FROM POWDEIRS 4 Sheets-Sheet 5 Filed April 10, 1962 Nov. 24, 1964 c. DEIBEL ETAL 3,157,914

AUTOMATIC APPARATUS FOR PRODUCING MEMBERS FROM POWDERS Filed April 10, 1962 4 Sheets-Sheet 4 United States Patent ()fiFice 3,157,914 Patented Nov. 24, 1964 Pennsylvania Filed Apr. ill, 1962, Ser. No. 136,488 6 Claims. (Ci. Iii-16) This invention relates to powder metallurgy and is particularly directed to automatic apparatus for the continuous production of compacted bars of indefinite length from powdered metals, ceramics and metalloids.

In application Serial No. 81,911, filed November 18, 1960, now abandoned, there is disclosed a process and apparatus for producing members from powders. In the above-mentioned application a pressing head of particular design is disclosed which has been found to be especially good for use in compacting powder materials. Further, a channel or trough die useful in producing continuous compacted green bars is also disclosed. Although compacted green bars of good quality are produced by the process and apparatus described in application Serial No. 81,911, the process is relatively slow and tedious.

Accordingly, it is a primary object of this invention to provide automatic operation of apparatus capable of continuously producing compacted powder bars.

Another object of the invention is to provide apparatus which is specifically adapted to the automatic production of compacted powder bars.

Other objects or" the invention will in part, be obvious and will, in part, appear hereinafter.

For a better understanding of the nature and objects of the invention, reference should be had to the following detailed description and drawings, in which:

FIGURE 1 is a view in elevation of one automatic apparatus capable of continuous production of compacted powder bars;

' FIG. 2 is a view in part in perspective and in part schematic, of an automatic apparatus and system capable of the continuous production of compacted powder bars;

FIG. 3 is a detailed showing in perspective of the structure adjacent the pressing area of the automatic apparatus of this invention;

FIG. 4 is a detailed showing in perspective of the die Wall and its support in accordance with this invention;

FIG. 5 is a showing in perspective of an endless chain of die wall sections in accordance with this invention; and

FIG. 6 is a view in elevation of the pressing head.

In carrying out the teachings of this invention certain critical considerations set forth in application Serial No. 81,911 must be observed. Thus, in compacting powder bar a layer of powder is disposed in a trough, or the equivalent thereof, and a punch or pressing head having a critical configuration is repeatedly reciprocated into the trough at a pressing station, each successive punch stroke overlapping a previously compacted area of powder so as to compact under high pressure progressively successive portions of the layer of powder material to a desired density. The layer of powder is intermittently moved between strokes of the punch so as to travel into and through the pressing station. The intermittent movement of the layer of powder is correlated to the size and shape of the punch so that the layer of powder is compacted in increment fashion to the final density. This results in a continuous green strip of substantially uniform density. Thereafter, the green strip may be sintered and heat-treated, or otherwise processed to produce a member having the desired strength and other physical properties.

The punch or pressing head has a pressing surface for contacting the powder. The pressing surface is comprised of a substantially flat leading portion and a trailmg portion which fairs into and is tangent with the leading portion. In general, the pressing surface presents a smoothly contoured surface in which the trailing portion rises continually and smoothly at an angle to the leading portion. No substantial segment of the trailing portion exceeds an angle of 15 degrees with respect to the leading portion and the trailing portion is wholly above the point of tangency.

The relation of the punch to the trough is such that the width of the punch is quite close to the distance between the side walls so that it substantially fills the cross section of the trough. In order to achieve the desired density in the powder compact, a final pressure of from 5 to tons per square inch, is exerted upon each successive segment of the powder layer by the punch.

In compaction, the trailing portion of the punch com presses the powder layer only partly to a portion fairing into a fully compacted portion beneath the leading portlon of the punch to which has been applied the maximum desired pressure. The punch and layer of powder are then disengaged and a relative motion is instituted between the punch and the powder for an incremental distance equal to a distance less than the length of the leading portion of the punch. The punch is then moved downwardly and an increment of partly compacted powder is fully compacted by the leading portion of the punch, and an increment of uncompacted powder is partly compacted. In practical operations the incremental horizontal movement of the powder layer relative to the punch may vary in distance up to three-quarters of the length of the leading portion of the punch. The overlapping compaction strokes described are necessary to obtain strong and uniform compacted bars.

There follows a description of automatic apparatus capable of carrying out the above process.

Referring now to FIG. 1, there is shown generally at Ill a press for the compaction of powders, while the structure associated with the press for the transport of powder into the pressing area and of compacted powder bar from the pressing area is indicated generally at 20. The press lit includes a ram shaft 12, a hydraulic cylinder 11 in which one end of the shaft 12. is positioned, and a pressing head 15 (shown in detail in FIG. 6) is fixed to the opposite end of the shaft 12. Also part of the press structure are the beams lid which support the press table 13, which is located below the pressing headlii.

An important element of the powder transporting apparatus 20 is the endless stainless steel belt 22 which passes through the pressing area between the pressing head 15 and the table 13 and around the belt pulleys 23 which are supported at the apices of a triangle by the frame 21. In the horizontal portion of the path of the belt 22 it is supported by the stationary anvil member 26 which presents a top surface somewhat raised above the surface of table 13. While in the horizontal path, the endless belt 2 moves in synchronism with a plurality of die wall sections 30 which are positioned on either side of the moving belt. The die wall sections 30 and the endless belt 22 form a channel die in which the powder is compacted. A rack section 31 is provided on each of the die wall sections. The die wall sections 30 are restrained against vertical movement by the hold-down fixtures 32 which will be described in some detail below. Movement of the endless belt 22 and of the die walls is provided by a motor (not shown) which operates a pair of split gear trains 36, 37, 38, 39, only one of which is shown in FIG. 1. The gear trains 37, 38 terminate in'a' pair of cylindrical gears 40 (see FIGS. 3, 4, 5) coupled to the rack 31 for moving the die wall sections 30, and shaft 39, which terminates in a gear (not shown) coupled to the gear 25, rotates the pulley 23' for moving the endless belt 22. It will be observed from the arrangement of the gear trains 37, 38, 39 that synchronous movement of the endless belt and of the die walls is obtained.

A hopper 5 for containing powder is supported on frame 21 by a flanged member 41. The hopper 5 may be provided with an adjustable gate 6 for controlling the powder flow.

In the pressing area, the die walls are each in contact with and supported by a back-up member 33 which is adjustably secured to the table 13 by the threaded members 34 which extend through elongated holes in the bottom plate of the back-up member into engagement with table 13. The back-up member 33 may be accurately positioned, when threaded members 34 are loosened, by means of the threaded adjustment members 35 which extend through a flanged portion 13' of the table 13 into contact with the back-up member 33.

A guide assembly for the ram shaft is accurately positioned with respect to the table 13. This guide assembly is similar to a die-set and includes a plate 16 surrounding and fixed to the ram shaft and slidably supported on the guide pins 17 and spring members 18. Guide pins 17 are secured to table 13.

As seen in FIG. 1, the endless belt 22, in the horizontal portion of its path, moves from left to right in the direc tion of the arrow 100. Similarly, the die Walls move in synchronism with the endless belt in the direction of the arrow. The powder is deposited on the endless belt from the hopper 5 either under the influence of gravity alone, or in combination with agitation provided by a vibrator. The powder on the endless belt 22 is carried into the pressing area. After compaction in the pressing area, the compacted powder bar continues its travel in the direction of the arrow; i.e., to the right as seen in the figure, and there may be passed directly into a sintering furnace or may be cut into desired lengths, or otherwise treated.

Referring now to FIGS. 2 and 3, the automatic operation of this powder compaction apparatus and system will be described. In the embodiment of FIG. 2, a hydraulic system is employed to impart to the ram shaft 12 of the press, the motion necessary to drive the pressing head of the press in its compaction strokes. In the hydraulic system, a pump 51 draws hydraulic fluid from a sump 54 through a conduit 55 and supplies the fluid to conduit 52 at pressure. The conduit 52 includes check valve 53 and communicates with pressure switch 54 and the upper end of hydraulic cylinder 11 of the press. Within the hydraulic cylinder 11 is positioned the piston head 56 which is secured to the ram shaft 12. A spring 57 is located within the hydraulic cylinder 11 and is positioned to urge the piston head 56 upwardly. A branch conduit 58 connects conduit 52 to a liquid dump valve 59 located in the sump 54. The liquid dump valve 59 is a normally closed ball valve having a spring 61 which urges ball 62 to closed position. A leakage return line 63 permits return flow to the sump of fluid which has leaked passed piston head 56 and also the small amount of fluid used in the pressure switch 54.

A liquid dump valve linkage 71 is provided for opening the liquid dump valve when required. The liquid dump valve linkage is actuated by a pneumatic system indicated generally at 81. The pneumatic system comprises; a reservoir 82 containing air or other gas under pressure, a conduit 83 connecting the reservoir to the solenoid valve 84, and air cylinder 86 to which valve 84 is connected by conduits 87 and 88.- The solenoid valve 84 controls the flow of air through cylinder ports 87 and 88 located at opposite ends of the air cylinder. In'air cylinder 36 there is provided a piston 89 connected to a piston rod 91 which, in turn, is connected to the operating arm 93 which is operatively connected to the liquid dump valve linkage 71. The direction of movement of the piston 89 is determined by the cylinder port through which air is admitted by the solenoid valve 84. When air is admitted through one of the cylinder ports 87' and 88', air is exhausted through the other of the ports. It will be seen that when the piston 89 is moved to the right, as seen in FIGURE 2, the operating arm 93 first will move the liquid dump linkage 71 downwardly permitting the ball 6210 close in valve 59. As the piston continues its movement to the right the operating arm 93 closes switch 94 which controls the pump motor 96. When piston 89 is moved to the left, the operating arm 93 first permits switch 94 to open (stopping the pump motor) and then the liquid dump valve 59.

As explained previously, the movement of piston 89 in the air cylinder 86 is controlled by the solenoid valve This solenoid valve is, in turn, controlled by a first means sensing the position of the ram shaft 12 and by second means responsive to the fluid pressure in conduit 52. The solenoid valve 84 has a single slide valve member which is actuated by a pair of solenoids 97 and 9S. Solenoid 97 is controlled by a circuit including a source of power such as the transformer 99, one terminal of which is connected to the common terminal of the solenoid coils by the conductor 101. The other terminal of solenoid coil 97 is connected to a first terminal of a microswitch 102 by the conductor 103. The second terminal of microswitch 102 is connected to the second terminal of transformer 99 by conductors 104 and 106. Solenoid is connected to transformer 99 by the common conductor 101. The conductor 107 connects the second terminal of solenoid coil 98 to a first terminal of pressure switch 54. The second terminal of the pressure switch 54 is connected to the transformer 99 by the conductor 106.

The sensing means and solenoid valve operate as follows: When the ram shaft 12 reaches the highest point in its travel the guide plate 16 contacts microswitch 102, closing the switch and thereby energizing solenoid 97 in solenoid valve 84. The solenoid actuates the valve slide member to admit air under pressure through port 87 of the air cylinder 86, and exhaust air through port 88'. The piston 89 is thereby moved to the right in the air cylinder. When, at the other extremity of movement of the ram shaft, the pressing head is compacting the powder in the die, the pressure in hydraulic cylinder 11 reaches a predetermined level whereupon pressure switch 54 closes. Solenoid 98 is thereby energized and the valve slide member 86 is actuated to admit air under pressure through port 88 of the air cylinder 86, and exhaust air through port 87.

As mentioned previously, the endless belt and the die wall sections of the apparatus of this invention are synchronously driven. It will be understood that the movement of the belt and die walls is continuous while the press is operating, except that just prior to contact between the pressing head and the powder, the movement of the endless belt and die walls is brought to a halt so that the powder is at rest during compaction. The means for doing this is shown in FIG. 2. Motor 131 is the driving means for both the endless belt and die walls, which it drives through the gear trains 36, 37, 38 and 39, described previously. The circuit for the motor 131 includes a power supply and a normally closed microswitch 132. The microswitch 132 is positioned in the path of the guide plate 16 of the press so that on the downward stroke of the pressing head microswitch 132 is actuated by the guide plate 16 to open the motor circuit and thus bring to a halt the movement of both the endless belt and the die walls.

One cycle of operation of the automatic continuous compaction apparatus will be described. Starting with the condition shown in FIG. 2, when the unit is turned on (power to all circuits) switch 102 (normally open) is in the closed position, the coil on solenoid 97 of the solenoid valve 34 is energized opening the advance port 87 of the cylinder to the air supply. This moves piston 89 and piston rod 91 causing operating arm 93 to rotate clockwise. As arm 93 rotates, the liquid dump linkage '71 with lift pin 72 is lowered, allowing the spring loaded ball 62 in the ball valve in the pump to close. As the lever continues to rotate to the extreme clockwise position, the pump motor operating switch 94 is contacted, thus turning on the power to the pump motor 96 by means of the operating solenoid 1.52 on the line starter 151. The pump motor operates pump 51 to pump the hydraulic fluid up conduit 52 through the check valve 53 and pressure switch 54 to hydraulic cylinder 11 causing piston 56 therein to move downward against spring 57. Before piston 56 has moved completely down the normally closed switch 132 is contacted by guide plate 16 opening the circuit to motor 131 and thereby stopping movement of the endless belt and die walls. As the pressing head 15 moves downward it contacts the powder fill between the die walls. As it compacts the powder, the hydraulic pressure in the system increases. When it reaches a predetermined pressure, the contacts of pressure switch 54 close, completing the circuit to the coil 98 of the solenoid valve 84. The solenoid valve operates, opening the retract port 88' to the air supply. The piston 89 retracts, rotatin the operating arm 93 counterclockwise. This moves the operating arm away from the pump motor switch 94 opening the circuit to the solenoid 152 on the motor line starter 151. The motor 96 stops and the hydraulic fluid pump 51 ceases to pump fluid. As the operating arm $3 is rotated to the extreme counterclockwise position the linkage 71 to the hydraulic fluid dump valve 59 is raised. Lift pin 72 raises the spring loaded ball 62 in the dump valve allowing the fluid pressure to be released and further allowing the fluid to be pushed back'into the sumpthrough conduits 52, 58 by the return spring 57 in the hydraulic cylinder. Under the combined influence of springs 18 and 57, the piston 56 and ram shaft 12 moves upward and contacts normally open switch 1612. Switch 102 closes activating solenoid 97 of the air valve 84 beginning a repetition of the cycle.

In FIG. 4 certain additional details of the structure of the apparatus of this invention are shown. One interesting feature which has been found to be critical is the contact of the die walls with the endless belt 22 and anvil 26. The die wall sections 3d? are generally plate-like in shape and have, with respect to the channel die of which they form a part, an exterior surface 231 and an interior surface 232. One longitudinal edge of the die wall section, which may be termed the drive-and-guide structure, is machined to a relatively thin edge forming a guide projection 233 which slides on table 13 in operation. The exterior surface of the guide projection 233 is provided with a rack 31 which runs the length of the die wall section. The interior surface of the guide projection is a guide surface 234 which mates in slidable relation with the edge surface 236 of the anvil 26. Between the guide surface 234 and the interior surface 232 of the die wall section is a shoulder 237 which, in assembled position, closely overhangs the edge of the top surface 238 of the anvil and contacts the endless belt 22 which rides on the anvil. This arrangement of parts and particularly shoulder 237 is quite effective in preventing powdered material from falling between the die wall and the anvil. It has been found that if these highly abrasive powder particles gain access to this region, wear quickly results which fatally affects the required close fit of the parts. Binding or jamming of the parts may also occur.

Another feature of interest shown in FIG. 4 is the linking means between adjacent die wall sections. Each die Wall section has a front end and a rearward end; the front end facing the direction in which the die wall section moves. The front end of each die wall section is provided with a pair of spaced pivot recesses 23} In each pivot recess there is a fixed pivot pin 241. The rearward end of each die wall section is provided with a pair of similarly spaced link recesses 242. In each link recess there is a fixed link member 243 which has a rearwardly extending portion in which there is provided a pin slot 244 which will accommodate pivot pin 241. In linking the die wall sections the front end of a first die wall section is brought adjacent the link members at the rearward end of a second die'wall section so that the pivot pins of the first section will slide into the pin slots of the second section. In order to accomplish this, the first section must form an angle of less than degrees with the second section as it is brought adjacent to it. Once the pins are seated in the pin slots the first die wall section is rotated through an angle greater than 90 to its final position in alignment with the second section. In order to permit the rotation of the die wall sections with respect to each other as described, the front exterior edge M6 of each die wall section is relieved to an appropriate radius. It should be noted that the linkage of sections is such that the rearward interior edge 247 of a die wall section moves away from the compacted bar as the section is rotated outwardly. The edge 247 thus cannot dig into or damage the compacted bar during rotation.

Thus, the die wall sections are joined in a manner such that they are capable of being rotated in a horizontal plane in a direction away from the endless belt. The die wall sections not in the pressing area of the press may readily be engaged or disengaged from each other. Thus, die wall sections may be added in the portion of belt travel before the endless belt enters the pressing area, and they may be disengaged and removed when the powder compact has been formed and the die wall sections have left the pressing area.

Further, a plurality of die wall sections may be linked in a pair of endless chains, at each side of the stainless steel belt. Such an arrangement is shown in FIG. 5 in which the endless chains of die wall sections merely slide on the flat surface as they are driven by the gears 46. Of course, tracks or other guiding means and additional driving means may be provided as required.

Another important feature of the invention is the manner in which side support is furnished to the die wall when the die wall sections are in the pressing area. The back-up plate has been described insofar as the means for holding the back-up plate to the pressing table and the means for adjusting the position of the back-up plate relative to the die walls are concerned. These aspects of the back-up plate are more clearly shown in FIG. 3. It is the contact face of the back-up plate which is of interest here and which is illustrated in FIG. 4. It will be noted that the forward portion of the back-up plate consists of a series of parallel horizontal ribs 369. The ribs 3% support a plurality of pins 361. Located in the recesses between the parallel ribs are a plurality of cylindrical rolls 352 rotatable on the pins 361 and of a diameter so as to extend slightly beyond ribs 366 into contact with the die wall section. Thus, there is provided a rolling contact between the rolls 362 and the die wall sections 34). This structure offers great support-while the die wall units are at rest and the powder on the endless belt is being compacted. At the same time, the die wall units may be moved past the back-up plate with reasonable case when the die wall units are in motion between compaction strokes.

Another suitable face structure for theback-up plate which has found application is one in which a sliding, rather than a rolling, contact is used, and provision is made to supply lubricant to the mating surfaces.

As mentioned previously, it has been found desirable to provide structure to restrain the die wall sections against vertical movement. The hold-down fixtures 32, as shown in FIG. 3, consist of an'angle iron 323 secured to the frame 21, an adjustable bar member 322 pivotable'on v I? 7 angle iron 323 about pin 321 and having a curved slot 319 therein, a bolt member 318 fitting through slot 31? and adapted to secure the bar member against rotation with respect to angle iron 323, and a rotatable bearing member 317 adapted to engage the top surface of the die wall sections. It will be observed that the bearing members 317 may be made to bear against the top surface of the die wall sections as tightly as required and may be firmly secured in place by the bolt 318.

There has thus been described an apparatus particularly adapted for the automatic and continuous production of compacted powder bars.

Since certain changes may be made without departing from the disclosure, it is intended that the accompanying description and drawings be interpreted as illustrative and not limiting.

We claim as our invention:

1. In an apparatus for the automatic continuous compaction of powder, a press having a pressing head thereon for compacting a powder, a trough movable beneath the pressing head, a hopper for dispensing powder into said trough, means for imparting movement to said trough, said pressing head capable of reciprocating movement toward and away from powder in said trough, the pressing head having a pressing surface thereon for contacting the powder, the pressing surface comprising a leading portion parallel to the trough base, a curved fairing portion comprising a surface tangential at one end to the leading portion and at the other end smoothly joining a trailing portion, the trailing portion being a smooth surface longer than said leading portion and angled away from the trough base at an angle not exceeding with respect to the leading portion, pressure responsive means capable of terminating the compaction stroke of the pressing head and reversing its direction of movement, means limiting movement of said pressing head in the opposite direction away from the trough and reversing its said opposite direction of movement, means for detecting approach of said pressing head to powder in said trough and responsive to such approach to halt movement of said trough so that during compaction the powder is at rest.

2. In an apparatus for the automatic continuous cornpaction of powder into bar form, structures for the transport of powder to a pressing station, for rigid confinement of the powder at the pressing station; for compaction of the powder and for transport of compacted bar from the pressing station after said compaction, said structures comprising, a press table, a pressing head, a rigid stationary anvil member supported on said press table and extending into and through the pressing station, a set of linked die wall sections adapted for movement along each side of said anvil, the anvil and die wall sections cooperating to form a channel die, each of said die wall sections having a guide surface at the lower end thereof in slidable contact with the anvil,'a shoulder adjacent said guide surface on each of said die wall sections overhanging and slightly spaced from the edge portions of said anvil, an endless belt slidable on said anvil in movement synchronized with the movement of said die wall sections, said endless belt closely fitting between said shoulder and saidanvil edge portions, and firmly anchored adjustable hack-up plates at the pressing station having contact with the exterior of said die wall sections to support the die walls against lateral movement during compaction of the powder, the pressing head havin' a pressing surface thereon for contacting the powder, the pressing surface comprising a leading portion parallel to the anvil-supported endless belt, a curved fairing portion comprising a surface tangential at one end to the leading portion and at the other end smoothly joining a trailing portion, the trailing portion being a smooth surface longer than said leading portion and angled away from the endless belt at an angle not exceeding 15 with respect to the leading portion.

3. The apparatus of claim 2 in which each set of linked die wall sections forms an endless chain lying in a plane perpendicular to the plane of the endless belt.

4. In an apparatus for the automatic continuous compaction of powder; a press including a press table; a pressing head for compacting powder; a trough movable beneath the pressing head, the pressing head having a pressing surface thereon for contacting the powder, the pressing surface comprising a leading portion parallel to the trough base, a curved fairing portion comprising a surface tangential at one end to the leading portion and at the other end smoothly joining a trailing portion, the trailing portion being a smooth surface angled away from the trough base at an angle not exceeding 15 with respect to the leading portion; the trough comprising a rigid stationary anvil member supported on said press table, a set of linked die wall sections adapted for movement along each side of said anvil, each of said die wall sections having a guide surface at the lower end thereof in slidable contact with the anvil, a shoulder adjacent said guide surface on each of said die wall sections overhanging and slightly spaced from the edge portions of said anvil, an endless belt slida'ole on said anvil, said endless belt closely fitting between said shoulder and said anvil edge portions; means for imparting synchronous movement to said die wall sections and said endless belt; a hopper for dispensing powder into said trough in predetermined amounts; said pressing hcad capable of reiprocating movement to compact and withdraw from the powder in said trough; hydraulic means for driving said pressing head in its compaction strokes to compact the powder at a pressure of at least 5 tons per square inch; firmly anchored adjustable back-up plates in contact with the exterior of the die wall section to support the die wall sections during compaction; pressure responsi as means capable of terminating the compaction stroke of the pressing head and reversing its direction of movement; means limiting movement of said pressing head in the opposite direction away from the trough and reversing its said opposite direction of movement; means for detecting approach of said pressing head to the powder in said trough and responsive to such approach to halt movement of said trough so that during compaction the powder is at rest; the synchronous movement of said die walls and endless belt being for a predetermined distance which is less than the length of the leading portion of the pressing head so that the powder in the trough is compacted by a series of overlapping strokes of the pressing head.

5. The apparatus of claim 4 in which each die wall section is pivotable in a plane perpendicular to the plane of the endless belt and in which each set of linked die wall sections forms an endless chain lying in said plane.

6. In an apparatus for the automatic continuous compaction of powder, a press including a press table, the press having a pressing head thereon for compacting powder, trough means for transporting powder beneath said pressing head, a hopper for dispensing powder into said trough means in predetermined quantities, means associated with said pressing head and said press table for guiding said pressing head into said trough means for compaction of powder, the pressing head having a pressing surface thereon for contacting the powder, the pressing surface comprising a leading portion parallel to the trough base, a curved fairing portion comprising a surface tangential at one end to the leading portion and at the other end smoothly joining a trailing portion, the trailing portion being a smooth surface longer than said leading portion and angled away from the trough base at an angle not exceeding 15 with respect to the leading portion, said trough means including a rigid stationary anvil member supported on said press table, a set of linked die wall sections adapted for movement along each side of said anvil, each of said die wall sections having a guide surface at the lower end thereof in slidable 3,157,914 9 10 contact with the anvil, a shoulder adjacent said guide against lateral movement during compaction of the surface on each of said die Wall sections overhanging P and slightly spaced from the edge portions of said anvil, References Cited in the file of this patent an endless belt closely fitting between said shoulder and said anvil edge portions, hold-down means in contact 5 UNITED STATES PATENTS W Said ie Wall sections to maintain said Close-fitting g f I sa mg), relation between a d shoulder and said anvil edge por- 894,282 igg 1 5 1959 and adjustable Plates firmly anchored to 2:925:619 Sindelar Feb. 23: 1960 the Press table and av ng contact with the die wall sec- 1 3,071,805 Merkle Jam 8,1963

tions adjacent the pressing head to support the die Walls I 3,032,853 Burdette May 8, 1963 

1. IN AN APPARATUS FOR THE AUTOMATIC CONTINUOUS COMPACTION OF POWDER, A PRESS HAVING A PRESSING HEAD THEREON FOR COMPACTING A POWDER, A TROUGH MOVABLE BENEATH THE PRESSING HEAD, A HOPPER FOR DISPENSING POWDER INTO SAID TROUGH, MEANS FOR IMPARTING MOVEMENT TO SAID TROUGH, SAID PRESSING HEAD CAPABLE OF RECIPROCATING MOVEMENT TOWARD AND AWAY FROM POWDER IN SAID TROUGH, THE PRESSING HEAD HAVING A PRESSING SURFACE THEREON FOR CONTACTING THE POWDER, THE PRESSING SURFACE COMPRISING A LEADING PORTION PARALLEL TO THE TROUGH BASE, A CURVED FAIRING PORTION COMPRISING A SURFACE TANGENTIAL AT ONE END TO THE LEADING PORTION AND AT THE OTHER END SMOOTHLY JOINING A TRAILING PORTION, THE TRAILING PORTION BEING A SMOOTH SURFACE LONGER THAN SAID LEADING PORTION AND ANGLED AWAY FROM THE TROUGH BASE AT AN ANGLE NOT EXCEEDING 15* WITH RESPECT TO THE LEADING PORTION, PRESSURE RESPONSIVE MEANS CAPABLE OF TERMINATING THE COMPACTION STROKE OF THE PRESSING HEAD AND REVERSING ITS DIRECTION OF MOVEMENT, MEANS LIMITING MOVEMENT OF SAID PRESSING HEAD IN THE OPPOSITE DIRECTION AWAY FROM THE TROUGH AND REVERSING ITS SAID OPPOSITE DIRECTION OF MOVEMENT, MEANS FOR DETECTING APPROACH OF SAID PRESSING HEAD TO POWDER IN SAID TROUGH AND RESPONSIVE TO SUCH APPROACH TO HALT MOVEMENT OF SAID TROUGH SO THAT DURING COMPACTION THE POWDER IS AT REST. 